Monday, July 23, 2018

The True Colors of Pluto and Charon

Three years after NASA's New Horizons spacecraft gave humankind our first close-up views of Pluto and its largest moon, Charon, scientists are still revealing the wonders of these incredible worlds in the outer solar system. Marking the anniversary of New Horizons' historic flight through the Pluto system on July 14, 2015, mission scientists have released the most accurate natural color images of Pluto and Charon. These natural-color images result from refined calibrations of data gathered by New Horizons' Multispectral Visible Imaging Camera (MVIC). "That processing creates images that would approximate the colors that the human eye would perceive - bringing them closer to 'true color' than the images released near the encounter," said Alex Parker, a New Horizons science team co-investigator from Southwest Research Institute, Boulder, Colorado. Because MVIC's color filters don't closely match the wavelengths sensed by human vision, mission scientists applied special processing to translate the raw MVIC data into an estimate of the colors that the eye would see. The colors are more subdued than those constructed from the raw MVIC color data, because of the narrower wavelength range sensed by the human eye.

Both images were taken as New Horizons zipped toward closest approach to Pluto and its moons on July 14, 2015; Charon was taken from a range of 46,091 miles (74,176 kilometers) and Pluto from 22,025 miles (35,445 kilometers).

Each is a single color MVIC scan, with no data from other New Horizons imagers or instruments added. The striking features on each are clearly visible, from Charon's reddish north-polar region known as Mordor Macula, to the bright expanse of Pluto's, nitrogen-and-methane-ice rich "heart," named Sputnik Planitia.

Preparations are well underway for New Horizons' next encounter, a flyby of Kuiper Belt object Ultima Thule, on Jan. 1, 2019 - a billion miles beyond Pluto. Currently about 3.8 billion miles (6.1 billion kilometers) from Earth - more than 40 times farther from the Sun than Earth - the spacecraft is operating normally and will begin making long-distance observations and measurements of Ultima in late August.

Added New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute: "Even as we celebrate the third anniversary of the historic exploration of the Pluto system - the most distant worlds ever explored - we're looking forward to the far more distant and record-shattering exploration of Ultima Thule, just five months from now!"